scott14

Aeronut,
Thanks for the idea's.... checked the seat pressure and it was fine.... removed the screen and placed a filter inline.


Av8tor,

I think it's close

I bent the metering lever up a bit more, and I'm now getting resolution on the needles. I can't hear the change, only see it on the tach.

I'm getting consistent RPM's of 6500 without heat, and 6700 with heat (18/8 Dynathrust)

I'm getting a new prop Friday 18/6 zinger.... see if it helps.

I also can get it to idle around 2300 without heat, and 2150 with heat (shakes like %$&%*^!!). I still would like a more reliable feeling idle[]

Needle reading:

Low: 2 turns out
High: 2 1/4 turns out

It doesn't transition as smoothly as I would like after idleing for a few seconds. This makes me think I'm rich on the low side.

I've tried to lean out the lowside needle, and that helped the transition, but it hurt the idle after coming off WOT.

Also.... Still wants to die if I come off WOT to idle[&o] I have to work the throttle to keep it running.

Why would I get higher #'s with heat on the glow plug at WOT... I would think it would be plenty hot without the heat?

aero nut

what size venturi on your carb??? also are you using stock muffler or open can type, you should be getting around 7800 to 8300 rpm's; maybe the prop, I use an APC 18x6W and getting 8300 rpm's when using a 18x6 MA was getting 7400 rpm's on a Ryobi 31, the transition is very smooth and the idle is at 2100 rpm's without heat, Is your engine used or new????
Also did you lift the reed valve stop lever to 1/8" this lets more gas to be burned and gives more RPM's.

scott14

Aeronut,

I'm using an 18/8 prop, so I suspect the number to be lower with the extra pitch.... I"ll be trying the apc 18/6w as soon as it gets in. Also going to try a 18/6 zinger wood prop.

the engine is used 2 ring with compression relief cuts, with a new top ring from bowman. I port matched the cylinder to the base, removed the gasket, and took the difference off the top of the exhaust port to make up for the gasket removal.

It uses a wt walbro from the list I found on this thread 11mm venturi.

Muffler is the billet one sold by paragon with adjustable tubes.

It transitions real good if I don't let it idle 2 long. It seems to load up and stumble going to WOT. I always thought that was being to rich on the low needle.

Using the OS plug you recommended... also used the saito plug... same results.

Maybe the 18/8 dynathrust is the problem... Could be to much prop at idle trying to pull it down? It really shakes when the idle gets below 2500.

sthomas14

I got a degree wheel and checked the duration:

Intake : 124
Exhaust: 155

Just trying to give you guys all the info I can to help me get it together.

I'm hoping the APC prop will pull my RPM's up.....

av8tor1977

My Feedback: (6)

How's your ring gap? It should be .003" or less. If it's wide, it will kill performance. A Frank Bowman ring almost always will give a power boost. Costs around 9 bucks.

Yes, it sounds like you're idle is still a bit rich if it blubbers on accleration and/or starts slowing down at idle after a while.

An engine that slows down after removing glow heat usually could use a bit more nitro. Some guys have had problems with detonation with higher nitro percentages in this application however, so I wouldn't worry about it if I were you.

The APC prop is going to help.

Good luck, you're almost there it sounds like,
AV8TOR

Ralphbf

My Feedback: (27)

It's not that I took the plunge but it was thrust pone me.
A friend was given Mac 28 or 32cc engine another friend couldn't make work.
It was completely setup with EI but Jack was tired of messing with it, took off the EI and gave it away.

I trades an OS LA 46 that I had taken off another plane straight across for it.
When I told him what I was going to do he laughed and said if it really worked more people would be doing it.

It was raining pretty hard here in California today so I set it up indoors in my shop.
I picked up a 16x8 prop put it on the engine, put in the glow adapter and a new F4 glow plug.
Rigged up a fuel tank and gave it a try.
It started right up. I adjusted the idle so it would run set the 2 needles and ran 8 ounces of fuel through it.

I refilled the tank and it started very easy with my starter. It seemed to Tachometer pretty good but since I was inside under florescent lights my Tachometer was useless. I removed the glow stick and the Idle dropped a few hundred rpm but still idled pretty good.

I used some 10 /18 fuel I had mixed with 2 parts gasoline. I plan on making up another batch of 15/18 and try again tomorrow.
This time outside where I can use a Tachometer.

I had expected to fight this thing for a couple of days, but as I always say " It's better to be lucky than good".

I used a Zenoah Gas-Glow plug adapter. It has the glow plug clear at the bottom which I thought was a good thing.
The problem is the glow stick was wrecked pushing it into such a tight fit.

It will still work for this application but nothing else.

I'll try to get a Tachometer reading and a picture tomorrow.

aero nut

Way to go Ralph!!! but try a fuel with less oil in it like the kind R/C cars use, they have less oil, I would try the 10/10 mix like av8tor's mix or try regular 15% nitro airplane fuel but diluted 50/50 with methanol, then 1 part of this mix with 2 parts of 91 octane gasoline and it should wor great.

mikenlapaz

Maybe a wheel collar with a soldered lead and a small piece of plastic for insulation. Clearances are tight. The first batch of them I got were apparently mis threaded 14mm x 1.25mm as they would not screw into the plug holes. My guess is that the 'bottoms' of the threads were not cut to full depth. The wall thickness on the adapters are minimal.
Anyone care to share any of their useful hints / secrets on working with these adapters, igniters, and glow plugs?

av8tor1977

My Feedback: (6)

I ground down an old socket to get good access to the glow plug for changing it. And my Dubro glow plug connector is made out of thin stainless steel and fits the glow plug just fine.

Yeah, one of the beauties of this system is not having oil all over the plane, so use less oil. Besides, the higher oil percentages will eventually cause carbon build up and engine seizure.

Have fun,
AV8TOR

scott14

Av8tor,

I'll check the end gap on the bowman ring..... also I've had the cylinder off for the porting, so the rings really haven't had any time to seat.... after I get the APC prop, I'll just run a few tanks of fuel thru it to let the ring seat, and see if it the power shows up

Again.... thanks a ton for your guys help.

scott14

All you gas/glow guys...


Here's a tip from when I raced Methanol gokarts. After the races, I would run straight wd40 for about 30 seconds.... cleaned all the remaining Methanol out of the carb, and killed every bug in sight

Those were double pumper tillison carbs, and I rarely would have problems from the methanol using this approach..... also won a few bets that the engine would run on straight wd40.

Gryohead

WD-40 uses propane for propellant that's why the engine runs, it is also a solvent and will start to rust the bearings along with the methanol.

scott14

Gryohead,

Never noticed bearing problems, but those were modified engines that only last a few weeks before I would put in new rod bearings / rings / valve springs. I would use ATF to coat everything during the rebuild.

Ralphbf

My Feedback: (27)

This is Av8tor's mix:

"Hi guys,
Only have a moment, but here goes:
A: My mix is as stated above; 2 parts high test gasoline to 1 part Byrons 10%--10% glow fuel.
B: I think if you go much below this methanol percentage, you will have problems with glow operation. "

I believe with a higher nitro ratio that this mix in my engine should work just fine.
At least that will be my next test.
I'll see what the Tach says and go from there.

Has any one ran alcohol from other sources than a cart shop or hot rod store such as a hardware store?

Having ridden 2 stroke motorcycles for 35 years I don't believe a little extra oil will hurt anything.
Especially in these short tests and I know a little extra will help seal the rings.
Another thing there was very little smoke from the exhaust, but the engine ran rather cool.

Ralphbf

My Feedback: (27)

WD-40 is basically kerosene and fish oil

sthomas14

I think i finally got it dialed in

I decided to switch to the carb from a poulan 46 I had......

Difference between night and day..... Holds a steady idle at 2050 no heat and smooth

I still want to play with the high side, but I got 7600 with the dynathrust 18/8..... Does that seem right? Thats almost 1000 RPM over the other carb I was having trouble with[X(]

It's nice to step away and watch it idle nice and smooth, and then walk over and give it WOT and watch it wind it's guts out

I can't wait to see what RPM's I get with the APC 18/6W...

It still wants to start backwards alot, any idea's about that?

RysiuM

My Feedback: (1)

It will, unless you use starter or figure out the way of flipping it. There is nothing in the engine that would stop it from turning it either way.
With spark ignition there is a timing on the spark plug - glow will fire with the same timing either way (a few degrees before TDC regardless of the direction the shaft is rotating).
Small glow engines have rotary valve on the intake (with front mounted carb). In pistan-timed intake or read valve on the intake the timing will be the same regardless of the direction the shaft is rotating.
So it is something you need to like to live with

av8tor1977

My Feedback: (6)

I'm kind of stubborn, and like to hand start my engines, (with a chicken stick). Mine often start backwards also. Just a touch of a starter has them running the right way every time, but like I said, I'm stubborn...

A lot of times if it's primed just right, or warm, you can just back bounce (flip) them against compression in reverse rotation and they will backfire and take off in the right direction.

Congratulations on your success!!!

AV8TOR

aero nut

Congratulations!!!!!!! you will really enjoy this Gas/Glow Hybrid conversion that you'll want to do every engine this way

sthomas14

Rysium,
I can live with it... If it's going to run like this , then its a small sacrifice.

Av8tor,
I'm stuborn also... if that hasen't already been made obvious.... I've been using my hand... guess I should get a chicken stick.... I did the back flip and it would start correctly part of the time.... not that big a deal I can live with it, besides I always have my starter at the airfield anyway.

Aeronut,

Your not kidding.... I already picked up a 42cc and 46cc Poulan to start messing with.... I'm building a 1/4 scale Gilmore "Red Lion" that calls for a 3 - 4 Cubic Inch gasser. I wonder what would be a good conversion for it?

Again..... Much thanks to all of you for helping me over the hump!

Ralphbf

My Feedback: (27)

Starting back wards is a sign of being to rich or slightly flooded.
This may need no adjusting on your part.

Simply flip it backwards and hope for the best

RysiuM

My Feedback: (1)

I think someone already mentioned that, but just be prepared for the plane to run backward after you start the engine. When the engine starts backward, the plane changes to "pusher" and may rolling back. Have your plane secured fom moving both directions (the usual rope on the tail will not work) and have you helper prepared for that "surprise" too. Otherwise you may end up chasing your plane from the "sharp" end[X(]

av8tor1977

My Feedback: (6)

Yeah, one of mine did that the other day. I was testing the engine and had the plane tied to a wall. I shut the engine down with the transmitter, but just as it was winding down to a stop it started back up backwards and backed into the wall. Luckily at such slow revs it didn't even ding the rudder!

AV8TOR

aero nut

I've always check the thrust of air when I start my engine making sure that it's blowing in the right direction before throttling any at all!!!!

RysiuM

My Feedback: (1)

That's a great tip. With front-carb glow engine you will immiedietly hear, when engine runs backward (the engine has caughing sound), but with side mounted carb it runs both direction with almost the same kind of noise. Checking the direction of thrust is easy and can be safly done (just don't stick your ear to the prop )